Switch



March 5, 1946. H L LAMBERT 2,395,885

SWITCH Filed Oct. 13, 1944 IN VEN TOR.

Patented Mar. 5, 1,946

SWITCH Harry L. Lambert, Enfleld, N. Y., asslgnor to Allen Wales Adding Machine Corporation, Ithaca,

Application October 13, 1944, Serial No. 558,545

(Cl. ZOO-80) Claims.

This invention relates to switches and particularly to those which make or break a circuit in response 'to centrifugal action, and is in the nature of a modification of the switch disclosed and claimed in my copending application Ser. No. 499,498 filed August 21, 1943.

An object of the invention is to provide an improved liquid type of switch which when rotated will make and break a circuit 'as the speed of rotation varies on opposite sides of a. predetermined speed; which will be uniform in its operation in all dlfierent positions in. which the switch may be placed; which will be sensitive at all speeds; with which the circuit will be made or broken within small limits of variations in the speed; which will be independent of gravity or surface tension for its action, and which will be relatively simple, compact, effective and inexpensive.

A further object of the invention is to provide an improved liquid type of switch, with which the speed at which it operates to make or break a circuit may be varied in a simple manner,

Other objects and advantages will be apparent from the following description of an embodiment of the invention, and the novel features will be particularlypointed out hereinafter in connection with the appended claims.

In the accompanying drawing:

Fig. l is a sideelevation of a rotatable shaft having mounted thereon a switch constructed in accordance with this invention, and an electric circuit associated therewith and shown diagram matically to illustrate the usefulness of the switch; and

Fig. 2 is a longitudinal sectional elevation through the switch per see.

In the illustrated embodiment of the invention, a shafti is mounted for rotation many suitable manner, from any suitable source of power. The shaft l carries a block or disk 2 of insulating material, Upon one end face of this block 2 is secured the base part of a U-shaped strip 3, the strip 3 being disposed with its face or cross part approximately radially with respect to the axis of rotation of the shaft l. One arm 4 of the U is adjacent the outer periphery of the block 2 and the other arm ii of the U is in' proximity to the axis of the shaft 4. The cross bar of the member 3 is rovided with a longitudinal slot through which the shanks of headed pins 6 pass into the block 2, with the heads of the pins 6 overlying the member 3 to confine it to the end face of the block 2, while permitting sliding radial movement thereon. The member and 45, so that the conductors l2 and 3 between the arms is provided with a pair of opposed, spring, arcuate clamp arms 1, only one being shown, which clamp between them a housing 8 containing the switch mechanism. The switch mechanism is shown separately in Fig. 2,

A screw 9 is rotatably mounted in a bearing it which is also carried on the same end face of the block 2, and may be rotated by a knurled button or head II. The screw 9 is threaded through an aperture in the arm 5 so that by turning the head ll of the screw 9, thescrew will, by its threaded engagement with arm 5, shift the member 3 in a direction radially of the shaft i, it being understood that the screw 9 is disposed approximately radially of the shaft l. The housing 8 has conductors l2 and I3 leading therefrom at the end nearest the axis of rotation of the shaft l, and these conductors are connected to metal collecting rings on the opposite face of the block 2. Brushes Hi and 15, disposed adjacent the coi looting rings, bear respectively on the collecting rings so as to maintain contact with the rings while the block 2 rotates. Wires I6 and El leading from line wires L and L under the control of a switch l8, are connected to the brushes it It running from the switch housing 8 will be connected in series with the line wires L and L Included in series in one of the wires l6 or ll, such as the wire [6 in the illustration, in an instrument M which may be a signal device, or the motor which drives the shaft, a relay, or any other instrument to be controlled by the switch mechanism in the housing 8.

Referring particularly to Fig. 2, the switch housing 8 is hollow to provide a sealed chamber 26. A tube or cylindrical wall 2! is provided in the chamber M, so as to extend from one wall substantially to the other end wall, but this wall H which is preferably impervious or imperforate for most of its length is vented at its ends to the chamber 20 outside of the tube. As shown this wall 21 extends from one end 22 of the housing 8 and terminates a short distance from the opposite end 23 01 the housing. The end of the tube 2| where it is connected to the housing end 22 is provided with apertures 24, but it will be understood that it is functionally immaterial which end of the housing the tube extends from. This enables gas to pass into and out of the tube at either end but not through the intermediate portion of the tube. While the tube is preferably imperforate, it is not necessarily so, because it primarily is a guide for a coherent body, as will be explained presently.

A body of liquid 25 is disposed in and partially fills the chamber 20 and this liquid is preferably a conductor of electricity. For example, water having a salt or acid dissolved therein is recognized as a good conductor of electricity, and liquid mercury is an excellent conductor of electricity. Mercury, because of its relatively low resistance, good conducting capacity and high density, is preferred as the liquid to be used.

Within the tube 2! is a coherent body 28 whose periphery approximately fits the inner periphery of the tube 2i, yet is slidable endwise of the tube freely. 'This body 26 is of greater density than the liquid 25. Disposed in the tube 2| is a helical coil spring 21 which acts between the body 26 and the end 23 of the housing, so as to urge the body 26 toward the end 22 of the housing. The

conductors i2 and i3 extend through the end wall 21?. of the housing, and within the housing terminate in exposed electrodes or conductors 2B and 29 which may terminate at different distances from the end 22, although both could terminate at the same distance from the end 22 if desired. The spring 2 normally urges the body it away from the end 23.

When the switch is rotating about the axis of shaft the liquid 25 will remain in the end of the chamber 2s farthest from the axis of rotation, and hence will be collected against the end 23 of the housing. As the speed increases, the

, centrifugal forces acting on the body 26 will urge body 26 of heavier density towards the end 23 or away from the axis of rotation, but this movement is opposed by the spring 21 and the centrifugal forces urging the liquid further into that end of chamber 20 with the buoyant action of the liquid on the body. At the lower speeds, the action of the spring 21 opposing such centrifugal forces on body 25- will keep the body from endwise outward movement. As the speed increases further, the centrifugal forces acting on body 26 will become large enough to overcome the spring 2? and the buoyant effect on the body due to centrifugal forces acting on the liquid 2.5, and as a result the body 26 will move radially outwardly from the axis of rotation. In doing so it will displace the liquid 25 in the opposite direction along the tube until the liquid engages with both of the electrodes 28 and 29 "1e chamber 28 to electrically connect them.

When the speed falls, the spring 21 will again become dominant and will urge the body 28 back towards the axis of rotation and the liquid 25 in the chamber outside of the tube 2! will recede n the shorter conductor 28 and thus open the t between conductors l2 and 13. Thus the-.. will be a critical speed on one side of which the liquid 25 will engage with the shorter conductor 23 and on the opposite side of which it will separate therefrom, and this making and breaking of the circuit in the liquid between the conductors i2 and may be utilized to control the instrument M in the nature of a signal device or the motor which drives shaft I.

When controlling a motor, the part M will act through a relay which controls the motor circult, so that when the rotation reaches a selected speed, the closing of the circuit between conductors l2 and i3 will cause an opening of the circult through the motor. The speed will then fall and a recession of the liquid 25 from conductor 28 will open the primary circuit between conductors i2 and i3, and this will again cause the completion of a circuit through the motor. When the part I! is a signal device, the operation of the signal at the critical speed will indicate that that speed has been reached or exceeded.

By shifting the switch distances from the shaft I, the speed at which the switch is effective may be varied, because when the switch is farther from the axis of rotation, the centrifugal forces acting on the liquid 28 and body 26 will be greater, and when the switch is shifted toward the axis of rotation, the centrifugal forces will be less for the same speed. Thus it is possible to turn the screw head II to various speeds at which the switch will open or close the circuit.

while the varying liquid level in the housing outside of the tube may be used to operate a switch in other ways, such as through a float, in which case the liquid need not be a conductor of electricity, it is much simpler to use a conducting liquid to connect the contacts or conductors within the housing.

It will be understood that various changes in the details, materials and arrangements oi parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. A switch comprising a housing having a sealed chamber with an inert gas, a body of liquid within and only partially filling said chamber, a coherent body within said chamber, of greater density than said liquid, and freely movable in a direction endwise of said chamber, whereby when said housing is rotated about an axis crosswise of the length of said chamber and nearer one chamber end than the other, the liquid and body will be urged by the centrifugal forces acting thereon and due to said rotation, towards said other chamber,end, a resilient element in said chamber yieldingly opposing movement of said body by said centrifugal forces, whereby the liquid level within said chamber will vary with the speed of rotation of said housing, and switch elements within said chamber and connected and disconnected by variations in said liquid level with variations in speed of rotation of said housing.

2. A switch comprising a housing having a sealed chamber, a body of liquid within and only partially filling said chamber, an inert gas in said chamber, a coherent body within said chamber and of greater density than said liquid, means within the chamber for guiding said body for movement in a direction from end to end of said chamber, a resilient element within said chamber and urging said body towards one end of said chamber, whereby when said housing is rotated about an axis nearer said one end of said chamher than the other, said liquid will be confined in said other end of said chamber by centrifugal forces and with said resilient element will urge said body away from said other end so as to allow the liquid to collect as completely as possible in said other end of said chamber, but yielding when the centrifugal forces acting on said body overcome those acting on said liquid and said element and force said body into said liquid that is conlined in said other end, to displace said liquid toward said one end, and conducting means in said chamber connected and disconnected by the varying levels of said liquid in said chamber with varying speeds of rotation.

3. A switch comprising a housing having a I of greater density than said liquid. said housing having means to guide said body for limited movement in a direction from end to end of said chamber, a spring in said chamber urging said body toward one end of said chamber, whereby when said housing is rotated about an axis nearer said one chamber end than the other end and crosswise of the length of said chamber, said liquid will be confined in said other end of said chamber and will urge said body towardsaid one end, and centrifugal forces acting on said body will urge it into the liquid collected in said other end and displace some of said liquid toward said one end for distances proportional to the speed of rotation, and conducting elements in said chamber connected and disconnected by the varying levels of the displaced liquid in said chamber with variations in the speed of rotation.

4. A switch comprising a housing having a sealed chamber with a tube extending from one end of the chamber towards the other and vented at both ends into the chamber, an inert gas in said chamber, a coherent body disposed within and substantially filling said tube crosswise but freely movable endwise of the tube, a spring interposed between said body in said other end of said chamber and urging said body toward said one end of said chamber, a liquid within and only partially filling said chamber, whereby when said housing is rotated about an axis nearer said one end of the chamber than the other. said body andliquidwilibothbeurgedintosaidotberend of said chamber and the liquid displaced from said other end by said body as the centrifugal forces on said body overcome said spring and liquid pressure to greater extents with increases in the speed of notation, and conducting elements disposed within said chamber outside of said tube and connected and disconnected by the varying levels of said displaced liquid.

5. A switch comprising a housing having asealed chamber, an inert gas in said chamber, a tube disposed in said chamber and extending substantially from end to end thereof and vented at both ends into the chamber around it, a liquid disposed within and only partially iiiling said chamber, a coherent body within said tube and substantially conforming in periphery to the transverse periphery of said tube but freely slidable endwise of the tube, said body having a greater density than said liquid, a spring interposed between said body and one end of said chamber in said tube and urging said body towards the other end of said tube, whereby when the said housing is rotated about an axis crosswise of the length of said tube and name:- said other end of said tube than said one end. the liquid will be confined in said one end and said body will be urged against the action of said spring and the centrifugal forces acting on the liquid, towards said one end of the tube to displace liquid in the opposite direction along the outside of the tube, and conducting elements in said chamber and connected and disconnected by variations in said liquid level on the exterior of said tube.

HARRY L LAMBERT. 

